I was looking at some arguments in favor of the existence of other minds and one in particular really caught my eye:

“If something like phenomenal conservativism is true, then since it strongly seems to us as if there are other minds, we have good reason to believe that there are other minds.”

I regard this as a rather bizarre piece of reasoning precisely because it seems to have gotten things backwards.

First, I would claim that in order for something to ‘seem to exist’ then it must be perceivable. Rocks, trees, and human beings are all things that seem to exist in virtue of their satisfying this ‘perceivability’ criterion.

But what about other people’s experiences? Do they seem to exist too? Not really, because other people’s experiences are never perceived. Unlike human bodies (which are perceivable), ‘other minds’ are not observable from a third-person perspective and, as such, fail to satisfy the ‘perceivability’ criterion. I don’t find a Cartesian theatre of visual experiences when I peal back a human skull. Instead there is nothing except a three-pound gelatin mass, and there is no hint that this gelatin mass ‘gives rise to’ or is in any way ‘identical’ with conscious experience. Where, then, are other people’s experiences? The compatibility between phenomenal conservativism and the existence of other minds begins to look grim.

I never encounter ‘other minds’ in the world. Instead, I only encounter other people to whom ‘mind’ is attributed to.

What would it even mean for people to seem to have experiences? I would say that this must mean their experiences must be inside their bodies somewhere. Inside their heads for example there is a Cartesian theatre of visual experiences, or something like that. But these things do not see to exist.

Solipsism suddenly doesn’t begin to look so absurd after all. It is a simple consequence from the rather benign and childlike observation that ‘other minds’ never make an appearance in the world. And this is what I believe Wittgenstein meant when he said ‘solipsism coincides with pure realism’. One can fully accept the world as it is while rejecting other experiences because these experiences simply are not part of the furniture of the world. There’s nothing egotistical, mad, or sociopathic about solipsism at all. In fact, it is entirely compatible with ‘common sense’ (phenomenal conservativism is supposed to be a version of a ‘common sense’ epistemology, right?).

There’s no absurdity in doubting the existence of other minds like there is when it comes to doubting other people.

Is it “egotistical” to call dream world solipsistic? No, and neither is it egotistical to call the waking world solipsistic.

I am not saying ‘other people’ do not exist. Other people truly do seem to exist. But other minds do not.

I find something pretty interesting about all of this. If the non-existence of other experiences is compatible with phenomenal conservativism and phenomenal conservativism is taken to be a “common sense” epistemology then this would make solipsism compatible with common sense. And this would do away with the straw man that solipsism is a “radically skeptical” position.

Returning back to the original question: How do other minds fit into phenomenal conservativism? To that I answer: they don’t. Phenomenal conservativism is actually the strongest tool in a solipsistic epistemology.